ISO 33820-3:2012 is the latest international standard for measuring the acoustics of open-plan offices. The methodology therein involves characterizing the decay of speech over workstations, with metrics that are based on speech sound pressure level and speech transmission index calculations. This paper presents preliminary results towards the quantification of the measurement uncertainty of the ISO 3382-3 method, which is not addressed in the standard, using repeated measurements made in several open-plan offices.